*{
    margin: 0;
    padding: 0;
}
#mainContent{
    display: flex;
    justify-content: center;
    font-size: 40px;
}
.op{
    margin: 20px;
    margin-top: 150px;
    cursor:pointer
}
#imgs img{
    width: 800px;
    height: 400px;
    display: none;  /* 设置所有图片隐藏 */
}